1. Field of the Invention
The present invention relates to an electronic apparatus in which a liquid coolant is used to cool a heat-generating component such as a CPU (Central Processing Unit). More particularly, the invention relates to a structure that prevents the liquid coolant from leaking from the circulating path.
2. Description of the Related Art
A CPU is incorporated in, for example, notebook-type portable computers. The heat that the CPU generates while operating increases as its data-processing speed rises and it performs more and more functions. The higher the temperature of the CPU, the less efficiently it operates. To cool the CPU, so-called “cooling system of liquid cooling type” have been developed in recent years. The cooling system uses a liquid coolant that has a far higher specific heat than air.
Jpn. Pat. Appln. KOKAI Publication No. 7-142886 discloses a cooling system of liquid cooling type, configured for use in portable computers that comprises a main unit and a display unit. The cooling system comprises a heat-receiving header, hear-radiating header, and a tube for circulating the coolant. The heat-receiving header is provided in the main unit and thermally connected to the CPU incorporated in the main unit. The heat-radiating header is provided in the display unit and located at the back of the display panel incorporated in the display unit. The tube extends from the main unit to the display unit. It connects the heat-receiving header and the heat-radiating header.
In this cooling system, the coolant is heated in the heat-receiving header as it receives the heat generated by the CPU. The coolant thus heated is transferred via the tube into the heat-radiating header. The heat-radiating header radiates the heat generated by the CPU, as the coolant flows through it. The coolant is cooled as the heat-radiating header performs heat exchange. The coolant thus cooled is transferred via the tube, back into the heat-receiving header through the tube. Back in the heat-receiving header, the coolant receives the heat from the CPU again. As the coolant is circulated, the heat is transmitted from the CPU to the heat-radiating header with high efficiency and the heat-radiating head radiates the heat. This enhances the efficiency of cooling the CPU.
In the cooling system of liquid cooling type, the coolant is circulated between the heat-receiving header and the heat-radiating header through the tube. The coolant may leak from the circulation path. The leaking may occur at, for example, the junction between the heat-receiving header and the tube. In the conventional cooling systems of this type, tube couplings are arranged at the coolant inlet port and the coolant outlet port. The tube has its one open end pushed into a tube coupling and is thereby connected to the heat-receiving header. To render the connection more firm and reliable, the junction between the tube and the tube coupling is tightened with a band. The band prevents the tube from being disconnected from the tube coupling.
The cooling system of liquid cooling type can maintain its efficiency of cooling the CPU as long as the coolant is smoothly circulated, even if the coolant leaks a little or contains bubbles.
If the coolant keeps on leaking from the circulation path, however, it will contact the CPU and the other electronic parts provided in the main unit. If the coolant contains antifreeze, it is electrically conductive. Particularly in this case, the coolant may damage the CPU and the other electronic parts, disabling the portable computer in some cases. Should the leaking coolant flow outside the main unit, it would spill over the desk or make cloths dirty, impairing the use environment of the computer.
The junction between the tube and the heat-receiving header may loosen as the tube deforms, assuming the same shape as the tube coupling. It is then no longer possible to prevent the coolant from leaking at the junction. In this case, the coolant may flow in the main unit.
A coupling structure that prevents liquid from the junction between two tubes is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 4-258591. The coupling structure comprises a packing and a fixture member, both shaped like a hollow cylinder and made of rubber material that contains super absorbent polymer. The packing is mounted on one end of the tube, and the fixture member is mounted on an end of the other tube. The packing and the fixture member bite each other, sealing the abutting ends of the tubes in watertight fashion.
The coupling structure, however, needs a special stopper for fastening the packing and the fixture member to the two tubes, respectively. Without the stopper, the fixture member may be displaced with respect to the packing when it is fitted into the packing. Further, both the packing and the fixture member need to have a plurality of projections so that they may bite each other.
Consequently, the packing and the fixture member are complex in shape. This raises their manufacturing cost. It should be noted that the coupling structure is one designed to couple pressure tubes for use in multi-story, apartment houses. They differ, in technical field, from those for used in apparatuses, such as portable computers, which incorporate electronic parts. Besides, Jpn. Pat. Appln. KOKAI Publication No. 4-258591 neither teaches nor suggests that the coupling structure may be used in cooling systems for use in electronic apparatuses.